TY - CHAP M1 - Book, Section TI - Ultrasound A1 - Shindler, Daniel M. A1 - Shindler, Olga I. A1 - Wright, Alicia PY - 2020 T2 - Practical Echocardiography for Cardiac Sonographers AB - Sound frequencies above the audible range.Familiar example: A dog whistle. SN - PB - McGraw Hill CY - New York, NY Y2 - 2024/03/28 UR - accesscardiology.mhmedical.com/content.aspx?aid=1175624922 ER -